muirhead



2 Sheets-Sheet 1.

A. MUIRHEAD 8v G. K. WINTER.

, Ouadruplex-Telegraph. No. 227,039. Patented April 27, 1880.

INVENTORS ma@ www@ N.PETERVS, FHOTO-UTHCGRAPMER. WASHINGTON. D C.

2 Sheets-Sheet 2.

A. MUIRHEAD 8v G. K. WINTER.

Quadruplex-Telegraph. No. 227,039. Patented April 27,1880.

Fly. 6. ffy. 7

N.PETEHS, PHOTQ-LITHOGRAPHEH. WASHINGTON. D C.

' UNITED v STATES PATENT OFFICEO ALEXANDER MUIEHEAD, OF VESTMINSTER, ENGLAND, AND GEORGE K. VINTER, OF MADRAS, INDIA.

QUADRUPLEX TELEGRAPH.-

SPECIFICATION forming part of Letters Patent No. 227,039, dated April 27, 1880.

Application tiled October 3, 1879. Fatonted in England November 12,1878.

To all whom it may concern:

Be it known that we, ALEXANDER MUTE- HEAD, doing business at 29 Regency street, Westminster, England, and a resident at Oakwood, Farquhar Road, Upper Norwood, London, England, and GEORGE Kirfr WINTER, at present residing at Arconam, in the presidency of Madras, in the Empire of India, both subjects of the Queen of Great Britain, jointly have invented certain new and useful Improvements in Multiplex Telegraphy, which improvements are fully set forth in the following specification.

Our invention is based on and constitutes an improvement upon an invention in duplex telegraphy set forth in the application for Letters Patent of even date herewith by Muirhead, Briggs, and Winter, and shown and described in Figures l and 2 in the speciticat-ion of Muirheads British Patent No. 4,590, of November l2, 1878.

'Ihe application and patent above referred to show apparatus consisting of a true or main line connecting the different stations, and at each station an articial line or compensatingcircuit, a split battery interposed between the main and artificial lines, a relay or receivinginstrument interposed between the battery and the earth, and short-circuiting or reversing keys, which apparatus is adapted for simultaneously transmitting a single message in each direction over a single wire.

The object of our present invention is to adapt that apparatus to the simultaneous transmission of two or more messages in the same or both directions over a single wire. Simultaneously transmitting two messages in the same direction we term biplex transmission. Simultaneously transmitting two messages in opposite directions we term quadrupleX77 transmission, and so on.

The essential characteristics of our invention are, first, the employment of the split-battery duplex system set forth in the patent and specication above mentioned; secondly', a novel method ot' working the relays or receiving-instruments, which consist of electromagnets provided with separate armatures having the capacity of being vibrated independently between contact-points common to them all by currents of varying strength and polarity.

The subject-matter claimed is specifically designated at the close of this speciication.

In setting forth our improvements it will be convenient to describe, irst, our improved method o'double-sending-thatis, sending two messages simultaneously in the same direction over a single wire, which we call bipleX telegraphy, and, secondly, the way in which we apply the split-battery or double-substitution plan of duplex telegraphy hereinbefore alluded to to our system,-so as to make it a true quadruplex telegraph.

In the accompanying drawings, which represent so much ofthe details of our improved apparatus as is necessary to illustrate the invention herein claimed, Figure l represents a plan or top view of one form ofonr improved relay or receivi11g-instrument, consistingof two electromagnets with the tongues or armatures interposed between them. Fig. 2 represents avertical transverse section through the same on the line 2 2 of Fig. l. Fig. 3 is a section through the contact-points, showing the relation of the tongues thereto under varying conditions hereinafter described. Fig. 4 represents a view of our improved double relay 5 Fig. 5, a vertical transverse section therethrough on the line 5 5 of Fig. 4. Figs. 6 and 7 are diagrams representing the arrangement of the apparatus on circuit. Fig. 7 shows the circuit-connections of the keys and batteries at a single station. Figs. 8 and 9 respectively represent two diii'erent methods of adjusting' the batteries for electro-motive force and resistance, one being adjusted on the shunt method and the other on the resistance plan. Fig. l() is a diagram representing our method of applying an electro-magnetic shunt to preventthe splitting up of signals. Figs. 11 and 12 represent the details ot' construction of the above-nientioned electro-magnetic shunt 5 and Fig. 13 is a diagram representing the arrangement of the apparatus, illustrating the winding of the coils of the relays and all the circuits and instruments necessary to the operation of the apparatus.

The Diplom arrangement-There are at the transmitting-stations two keys, one for the use IOO of each operator, and so arranged in connection with batteries that in the several positions of the keys the values of the battery strengths applied to the line, considered algebraically, which is very convenient in questions of this kind, are as follows, calling the two keys A and B:

Both keys at rest +3 Key B depressed, A at rest l +1 Both keys depressed. -1 Key A depressed, B at rest 3 The arrangement of the keys and connections by which we effect this is hereinafter described.

At the` receiving-station we have an ordinary polarizedrelay, such as Sieinens, adjusted to break the local circuit when the current is plus, and to complete it whenever the current becomes minus a local sounder or other receiver connected with this relay records the depressions of key A.

Ne have also in the main circuit, at the receiving-station, a double-tongued rela-y, which is used for completing the circuit ofthe sounder or receiver intended to respond to the movements ofthe key B. This double-tongued relay, which forms an important feature of our invention, is so arranged that in order that the local circuit should be completed it is necessary for both tongues to be against their respective contact-points.' To accomplish Ythis we either insulate the tongues and cause the contact between tongue and tongue to be conipleted through the contact-points, which, in this case, are connected electrically with each other, or we insulate the contact-points, and then cause the contact between point and point to bc completed through the tongues, which, in this latter case, are, of course, connected together.

The polarity and adjustment of the tongues are so arranged that the contact between one tongue audits pointis only broken when the cu r rent is +8, and that between the other tongue and its point is only broken when the current is 3. With the intermediate strengths of +1 and -l both tongues are in contact with their points and the circuit ofthe relay is complete. Thus the local circuit is broken when the eurrent is either +3 or +3, but it is closed when the current is either +1 or +1.

Both the contact-points are iixed to the saine carrier, and things are so arranged that when once the contact-points have been individually adjusted their further adjustment for ordinary changes in strength of the currents is made simultaneously by 011e and the same motion ofthe carrier.

0n very long lines it may be necessary to use a local relay to work the recorder, the local circuit of the second relay being coinpleted hy the relay we have described; but this will not be generally necessary.

Figs. l andlrepresent, respectively, a plan and section of one form of an improved double relay. In this form both tongues a' y play between the same pole-pieces p p of the electro-magnets E E. The tongues are polarized oppositely by a permanent magnet, D, so arranged that one end of it polarizes the upper tongue and the other end polarizcs the lower tongue. Two other magnets, F, polarize similarly. the cores of the electro-magnets E E. These electro magnets are placed one on each side of the tongues and at right angles to them. The pole-pieces of the electro-magnets are dat pieces of soft iron, of the same width as the core, and continued vertically above and below the cores across the flanges sufficiently far to envelop both tongues in their action. The tongues are caused to play as nearly as possible at equal distances above and below the axis of the cores, so that the action on them may 'neas uniform as possible.

The contact-points t' 'i' are on the same side of the carrier and one above the other. They are insulated from the frame-work of the relay and from each other, contact between them heilig completed through the tongues only when both tongues are against their respective contact-points. The requisite bias is given to these tongues by approximating them to one or the other of the pole-pieces by means of set-screws on blocks e e ofthe carrier G.

The three positions of the tongues ft' and y, corresponding with the currents +3i1tl3 depressed) and 3, respectively, are shown in Fig. S-that is to say, first, when both keys are open or at rest the upper tongue, a', is adjusted to fall on its insulated stop and the lower tongue, y, on its contact-point; second, when key B is depressed or closed and key A is at rest or open, or when both keys are depressed, both tongues fall back on their respective contact-points; third, when key A is depressed or closed and key B is at rest or open the upper tongue falls back on its contact-point and the lower tongue on its insulated stop.

After thc first adjustment of the tongues by means of the set-screws on the carrier, their further -adjustment is made by moving the whole carrier G by means of the slow-motion screw j', which works in a nut underneath the carrier.

It is evident that the action of any current passing through the coils of the electro-11mgnets is to cause the electro-magnets to act oppositely on the upper and lower tongues in consequence of their opposite polarity. Thus, if a plus current tends to cause the upper tongue to move in the direction of its insulated point, a minus current will have the same effect on the lower one. The adjustment ofthe tongues is such that it requires a strength of +3 to act thus upon the upper tongue and 3 to act in the same way on the lower tongue. If the current has either of the intermediate strengths of +1 or +1, the strength is insuficient to move either of them against their contact-points contrary to the bias given them, and consequently both tongues are incontact IOO IOS

IIO

with their respective contactpoints and the local circuit of the relay is complete.

When the current changes rapidly from +3 to -3 the lower tongue leaves its -contactpoint before the upper tongue has time to make contact. It. is only when this change is retarded that any difticulty is experienced in workin g the local instrument direct with this relay. If the instrument is a recorder, the si nals are perfect, as the effect of retardation is only to cause a slight trembling of the armature against its upper limiting-stop, and is insufficient to atiect the record.l

With sounders there is an inconvenience which can be remedied by rising an extra local relay to complete the circuit oil the sounder, the local circuit through the coils oi' which eXtra relay being completed by the double relay we have described. rIhis arran gement will probably only be found necessary on very long lines, or when any considerablelength is submarine or subterranean.

Another form of double relay, which has been found to be equally good and in some respects more convenient, is shown in Figs. et andA 5. In this form the tongues a' y are polarized in the same sense-that is, the saine polarity imparted to them by the permanent magnets D D. The tongues in this form are insulated from the frame-work of the relay and from each other, and contact between them is established only when both tongues are against their respective contact-points, which, as in the former case, are iixed to the same carrier and the same side ofit; but they are uninsulated. The electro-magnets E E E E are, in this case, polarized by the ends of the two permanent magnets D D', the other' poles of which polarize the tongues, so that all four cores and pole-pieces have the opposite polarity to that of the tongues x y which play between them. rIhe action of the currents on the tongues is, in this ease, precisely similar to that which we have already explained in reference to the other form ot' relay. In this ease, however, the polarity of the two tongues is the same; but the polarities of the pole-pieces between which they play are aii'ected by the currentin opposite sense-thatis, the polarity of one set is increased and that of the other diminishedand consequently opposite motions result in the tongues, as in the former ease. The adjust-ment ofthe relay-tongues in FiO. et corresponds to the sequence -l-l-l-S-l--l- 7.

We have described our system only as worked by the series of currents +3+1.-l-3, because this series, being symmetrical on each side of zero, is generally more economical than any other series for biplex working; but it is evident that it is not necessary' that the middle ofthe series should correspond withno current. The principle on which the method depends is, that with a series of Jfour currents, while the local circuit of one receiving-instrument is completed when the current strength has a value on one side of the middle of the series,

and is broken when the current has a value en the other side, the biplex relay completes the Y circuit while the current has a value corresponding with either of the two intermediate numbers ofthe series, and breaks the local circuit when the current strength corresponds with eitherot' the extreme numbers. VVlhus the series may be 0-1-1-5-2-ior +1+35 +7, &c. Thealaplication of this remarltwill be seen when we describe our method ot multiplex telegraphy, in which the same principle is applied in a more general sense.

rlhere are two ways ot' producing the variations oil currents required First. `\Ve may join the batteries and keys Aas shown in Fig. (i. In this'tgure, A A are 4reversing-keys, and S S' are simple short-circuiting keys. When the keys are at rest there are two series ot' 3u cells connected to the true and a-rtiiicial lines respectively. Below the shortcircuiting keys are 2n cells, and above them n cells on each side. By closing the short-circuiting keys we reduce the battery from in cells to n cells. By pressing the reversing key A or A the battery, whether of the power el" n or 311 cells, is simply reversed. The relays are placed between the middle ot' the battery and earth.

Second. The batteries may bejoined up with ltwo reversingkeys, A B A B', at each station, as in Fig. 7. ln this arrangement the keys B B separate the batteries into two portions, ot' which one contains 2n cells and the other n cells. lVhen these keys are at rest the connections are along the continuons lines of the drawing and the two portions ot' the batteries are acting in the same direction, so that the current is n-l-nzn. Then these keys are depressed they reverse n cells ot' the battery, so that we have only 2li-11:11 cells acting. The keys A 'and A, when depressed, simply reverse the current acting on the distant station, whether it is 3u or only n, as before.

The mechanical construction ci' the keys (which are such as are well known as reversing-keys) and the detail ot` their connections are shown by Fig. 7.

Fig. 13 illustrates two stations connected up according to the quadruplex system above described. A B Al Bf, t'our reversing-keys, constructed as shown in Fig. 7; (t a', two ordinary polarized relays, which answer to reversals ot' current, whatever be the strength 5 b b, two doubletongued relays, whose tongues a y are adjusted so as to be both on their respective contact-points whenever the current is l or -l, and thereby working the local apparatus connected therewith.

To explain the operation of these relays under the various strengths oi' currents employed wewill go through the separate cases scritti/im.

. First. Then beth keys A 13 are open a current ot" +3 is to line. No signal is produced on either localcircuit, because thetongue of relay a is held over against its insulated stop IOO IIO

when current is positive, and in the doubletongued relay the tongue x is adjusted to break contact with the local circuit when current is +3. (First position shown in Fig. 3.)

Second. When key B is depressed and A at rest the current on line is +l, and only the relay b answers. The current being still positive rela a does not workbut the reduction ofthe strength of the current from +3 to +1 causes the tongue .r of the double-tongue relay b to make contact with its local circuit, thereby producing a signal. (Second` position, Fig. 3.)

Third. When both keys are depressed the strength of current online is reversed and reduced to 1. Both relays answer-relay a because of reversal of current, and relay I) because both tongues x and y make contact with local circuit. (Second position, Fig. 3.)

Fourth. When key A is depressed and B at rest only relay a works. Current on line in this case is 3. Relay a works because of reversal of current. Relay b does not work because tongue y is adjusted to break contact whenever current becomes 3. (Third position, Fig. 3.)

Although these plans have only been described as giving the ratio :h3 to il as the battery-powers employed, yet it is obvious that by changing the position of the keys B B in the existing circuit we mayin either plan alter the ratio as we please.

)When there isla want of uniformity in the batteries, balance may be perfect for keyA, but imperfect for key B. )When key B is a shortcircuitingkey this may be remedied in the following way, (see Fig. 8:) A few cells may be placed between the two sections ofthe battery and these cells shunted by slide resistance, such as shown in the patent and application above mentioned. It is evident that the adj ustment of this slide will not aii'ect the balance as far as key A is concerned, but it will affect the balance for key B in practice. Therefore we tirst adjust the artificial line to obtain balance when key A is worked, and then adjust the balance for key B by means of the slide.

Wlheu key B is a reversing-key We arrange matters as in Fig. 9. Two resistances, i' r', are inserted, as shown in the figure. It is evident that the alteration of these resistances will not affect the balance as far as key A is concerned; but it will affect the balance when key B is worked, as these resistances are eX- ternal to this key. Ve therefore irst adjust the artitcial line to obtain balance when key A is worked, and then adjust the resistances r r so as to obtain balance when key B is worked. These resistances may be conveniently arranged so that one is increased and the other decreased, and vice versa, simultaneously. These arrangements will not be found generally necessary; but they are useful as a precautionary measure in case the batteries get into bad order.

It is, of course, very essential that the reversal of current through the double relay should be as rapid as possible, and as on long lines the tendency of the capacity ofthe wires is to cause a retardation in this reversal, it is advisable on such lines to adopt the following plans to counteract as far as possible the effect of this retardation First, we may connect across the reversing-key A, between the true and artiicial lines, the wire `forming the coils of an electro-magnet, as shown at C in Fig. l0; second, we may connect the wires of a second electro-magnet as a shunt on the doubletongued relay, as shown at H in Fig. l0.

It is advisable that the resistance of the electro-magnet at C should be at least equal to twice that of theline, and that at H atleast equal to that ofthe relay it shunts.

The electro-magnets may be of the wellknown closed horseshoe form, as shown in section ot' Fig. 11;- or they may consist of a single rod of soft iron, with iianges, also of soft iron, and a cylindrical casing ot'iron closing over the wire and connecting magnetically flange with flange, as shown in section in Fig. l2, as is well understood.

When it is necessary to compensate for static induction we prefer to use Muirheads well-known inductive resistance for, the artiicial line.

By carrying on the same principle further 'the quadruplex arrangement may be added to and made multiplex. Thus, for instance, in triplex telegraphy. which may be duplexed, we have three keys and arrange the currents as follows: Let a A b B c C represent the three keys, the small letters meaning that the key is at rest and the capital letters that the key is depressed. Then currents are- The recorders corresponding with A and B are worked as in biplex telegraphy, while that corresponding with C is worked with two double-tongued relays, or one relay with four tongues, which is better. Two tongues complete the local circuit between +5 and 5. The other two tongues short-circuit the recorder at +1 and 1; or one pair of tongues may close or open the circuit between +5 and +3, and the other pair may close or open it between -3 and 5. In either case a relay acted on by the local circuit of this compound relay is required to work the recorder.

It is of importance that the electro-magnets in the double or quadruple tongued relays should be small.

)Ve do not, however, herein claim this Sextuplex system or apparatus, as we contem- IOS IIO

plate making it the subject of another appli cation for Letters Patent oi' the United States.

We claim as our invention- 1. A telegraphic relay or receiving-instrument consisting ofthe combination, substantially as hereinbefore set forth, of electro-magnets and separate tongues or armatures interposed between the same set of magnets, and having the capacity of vibrating independently between adjustable contact-points electrically common to both armatures.

2. The combination, substantially as llereinbefore set forth, of a telegraphic circuit and a relay or receivinginstrument having separate armatures vibrating independently between the same set of electro-magnets and between contact-points electrically common to both armatures.

3. The combination, substantially as hereinbefore set forth, of a set of electro-magnets, separate armatures interposed between them, and having the capacity of vibrating independently, corresponding contactpoints and back-stops, mechanism for adjusting the armatures relatively to the poles of the electro-magnets, a carrier on which these contact-points and back-stops are mounted, and mechanism for adjusting said carrier.

4L. The biplex telegraphic apparatus hereinbefore set forth, consisting of the combination, in a telegraphic circuit, of a main line connecting two stations, and at the transmitting-station a battery, a short-circuiting and a reversing key (Or two reversing-keys) interposed between the sections of the battery, and at the receiving-station two relays, one an Ordinary polarized relay, the other consisting of a set of electro-magnets having two separate interposed tongues or armatures capable of vibrating independently, and having contact-points electrically common to both armatures,'whereby two messages simultaneously may be sent in one direction over a single wire.

5. The quadruplex telegraphic apparatus hereinbefore set forth, consisting of the combination, in a telegraphic circuit, of a true or main line connecting two stations, and at each station an artificial line or compensating-circuit, an interposed split battery, two separate receiving apparatuses or relays interposed between an intermediate point in the battery and the earth, one an ordinary polarized relay, and the other consisting Ot' two separate tongues or armatures having the capacity of vibrating independently between the same set of electro-magnets, and having contact-points electrically common to both armatures, and a shOrt-circuiting and a reversing key (or two reversing-keys) at each station, whereby two messages simultaneously may be sent in either direction over a single wire.

6. The l1ereinbet'oredescribed improvement in the art, method, or system of multiplex telegraphy, which improvement consists in simultaneously transmitting in each direction through a telegraphic circuit currents of differing strengths and polarity and reproducing them upon separate instruments, one an ordinary polarized relay responsive to the eX- treme values of the series adopted, the other havin g separate armatures interposed between the saine set of electro-magnets and responsive to the intermediate values of said series, and adjustable, substantially as herein described, to control a single local circuit.

ALEX. MUIRHEAD.

G. K. WlNTER.

Vitnesses to the signature of Alex. Muirhead:

A. M. DrrLOcii, T. JOHNSON. Both 0]"29 Regency Street, lfVestm/iaster.

Witnesses to the signature of George Kitt 'Vinter:

JAMEs T. MORGAN, Soir., Madras.

En. D. SYLVA, Clerk to lll'essrs. Taster t@ Wilson, Solicitors,

Madras. 

